1. Field of the Invention
The present invention relates to a process for treating a mixture of an oil and a copper chlorophyll extract with a solvent to render such mixture e.g. suitable for making microcapsules which contain a liquid core material comprising a mixture of oil and copper chlorophyll, said microcapsules e.g. being particularly suitable for use in oral care products.
2. The Related Art
It has already been previously suggested in the art to include microcapsules which contain an oily core and colouring agent in oral care products, primarily to impart a "speckled" or "spotty" colouring effect thereto. Thus, for example, GB-A-1,381,444 (Blendax) describes microcapsules having a transparent shell material encapsulating a solution or suspension of colouring matter in a physiologically inert solvent such as paraffin oil. These microcapsules can be included in toothpastes to impart a speckled colouring effect thereto. The colouring materials are colouring agents or pigments such as various C-reds, C-blues, and C-greens, the latter including C-green 8 which is a mixture of a copper chlorophyll complex and a copper chlorophyllin complex. These microcapsules can be made by well-known encapsulation processes, such as coacervation, using e.g. gelatine as the encapsulating material.
However, we have found that it is not possible to obtain acceptable microcapsules according to this prior proposal when using copper chlorophyll as the colouring agent. Dissolving copper chlorophyll in the paraffin oil gave a precipitate of small, blackish particles when added to water, thus making the mixture unsuitable for obtaining acceptable microcapsules by means of coacervation.
In EP-A-0,711,544 (Kao) microcapsules for use in dentifrice compositions are described, which contain agar as the coat-forming material, and core material which may consist of a great variety of dentifrice ingredients and vehicles therefor. Among these dentifrice ingredients copper chlorophyll is also mentioned, and among the vehicles natural fats and oils as well as minerals oils are mentioned. While various production methods, including coacervation, are mentioned, a double nozzle dropping method is preferred to make the microcapsules.
In some of the working examples, microcapsules are described which contain as core material a medium chain triglyceride and sodium copper chlorophyllin.
However, sodium copper chlorophyllin is water-soluble, and we have found that it is not possible to obtain acceptable microcapsules which contain a core of an oil and sodium copper chlorophyllin by means of coacervation according to this prior proposal. A green sludge was formed at the oil/water interface during the emulsification step, which prevented capsule wall formation. The same was found when using copper chlorophyll instead of the sodium copper chlorophyllin.
Chlorophyll extracts are usually obtained by suitable extraction of plant leaves such as alfalfa, grass, nettles.
The extracts normally contain chlorophyll a and b, as well as a number of other ingredients such a pigments, carbohydrates, waxes, fats, oils, salts, proteins and xanthophyll.
Copper chlorophyll extracts are usually obtained by replacing in the chlorophyll extract the magnesium ion at the centre of the porphyrin ring by copper.
Commercial grades of copper chlorophyll extract (INCI name: Chlorophyllin-Copper Complex or CI 75810; EINECS No. 234-242-5) are usually mixtures of copper chlorophyll extract and a vegetable oil, containing up to 15% copper chlorophyll.